Desire is a reliably unreliable guide to happiness, as Alain de Botton notes in “The Architecture of Happiness,” the fifth or sixth book from the prolific professional intellectual who has tackled everything from status anxiety to sex. In it, the author observes that bad buildings are like bad relationships, “an example expressed through materials of the same tendency which in other domains will lead us to marry the wrong people, choose inappropriate jobs and book unsuccessful holidays: the tendency not to understand who we are and what will satisfy us.”

Enter the decorator, for those who are able to afford his or her services, which is to say, the stagecraft that turns a dog into a jolie laide. Or at least the ability to make choices that would paralyze others, those of us for whom an ugly room — or perhaps an empty room, to misquote Mr. de Botton — “can coagulate any loose suspicions as to the incompleteness of life.”

At the 41st annual Kips Bay Decorator Show House, held in a slim limestone town house on East 64th Street, 18 designers have attempted to banish such existential anxieties by ricocheting between two extremes to fill its five floors.

“We do go back and forth,” said Jack Levy, a deep-voiced Texan with a taste for the maximalist expressions of ’40s French, ’50s Italian and ’60s American furniture and objets. “Is it enough? Is it too much?”

Mr. Levy said he decided early on to practice the sound decorating principal of horror vacui in his space, a fourth-floor sitting room he wrapped in a loopy Fornasetti wallpaper upon which tropical fish as big as your hand swam woozily in a brown sea. He also deployed aqueous silk taffeta curtains piped with charcoal and terra-cotta silk charmeuse; a pair of exotic wood cabinets in the style of Leleu on either side of a black marble fireplace topped with a dizzyingly amoebic-patterned oval encaustic painting borrowed from his best friend; and a delicate 19th-century French desk and chairs upholstered in a terra-cotta pink Fortuny silk damask. Then he woke up with a start a week or so ago, he said, and worried that he hadn’t done enough.

“We have our fears, too,” Mr. Levy said. “You have to be confident, but you have to be humble enough to ask, ‘Am I doing the right thing?’ ”

As it happens, Richard Sharp, the owner of this long-neglected property, was thrilled with Mr. Levy’s ministrations. “He asked me if he could keep the wallpaper and the curtains,” said Mr. Levy, who estimated the cost of the contents of his room at nearly $300,000. “Which is not only a supreme compliment, but something that makes my life much easier, since in a show house you usually have to remove your wallpaper and paint everything white.”

Decorating paralysis is a state that Mr. Sharp, a partner at the Milbank, Tweed, Hadley & McCloy law firm, says he is all too familiar with. Ten years ago, he bought this house for $6.58 million and never moved in. (He lives in a two-bedroom rental a few blocks north.) It is the second time he has done such a thing.

“I owned a place at the Majestic and never moved in there either,” he said. “This is going to make me sound strange, but I care too much about the details. I would want to pay attention to every color and every hinge. I’m visually oriented, and so when I sit down to think, ‘Do I want to take on this project?’ it’s overwhelming.”

Mr. Sharp, 64, a collector of Hudson River School artists and the chairman of Olana, the Frederic Edwin Church estate in Hudson, N.Y., said that when he asks his friends to recommend an architect, they tell him he needs a psychiatrist instead. So for years, he has used the house on 64th Street only to store his art.

It was Asher Alcobi, a real estate broker whose office is on the same block as the house, who suggested that Mr. Sharp give up the place to Kips Bay, the boys’ and girls’ club that provides after-school programs for children ages 6 to 18. Fifteen percent of the group’s operating funds are derived from the show house (tickets are $35).

There has always been a disconnect between the fantasy worlds depicted in the show house and the 12,000 children Kips Bay serves, more than half of whom live below the poverty line. But Mr. Sharp said that contributing the use of his house beats just writing a check, and in return, he would receive what Mr. Alcobi called “branding by Kips Bay,” a selling point should Mr. Sharp choose to list the place.

Not counting the designers’ own labor (about a month’s worth for each), creating a room in the show house costs a designer, on average, about $50,000, said Bunny Williams, the show house chairwoman. While materials like paint and fabric might be donated, the designers pay their installers and fabricators out of their own pockets.

Relationships are the back story. This was the first show house for Kristin McGinnis, a 38-year-old designer who once worked for Stephen Sills and James Huniford, and cut her teeth decorating the Upper East Side apartment of Agnes Gund, the Museum of Modern Art’s president emeritus. Ms. McGinnis’s best friend from sixth grade is Elliott Hundley, a bricolage artist who just wrapped up a solo exhibition at the Andrea Rosen Gallery in Chelsea. For Ms. McGinnis’s debut, Mr. Hundley made a poetic snarl of driftwood, string and neon that she hung from the ceiling of her dining room. Along a wall, a charred bronze console by Vincent Dubourg, a French conceptual artist, that Ms. McGinnis begged from another friend, was devised in two exploded sections, suggesting a post-apocalyptic dinner party among the wreckage.

Last week, Mr. Sharp saw the house for the first time. He had been to Istanbul to deliver a speech, he said, and when he flew back, he was so excited he dropped off his bag in the lobby of his apartment building and came straight to the show house.

“It was a visual overload,” he said. “But in a beautiful, magical way. I’m not going to get granular about the objects, but I saw so many wonderful things. The jet lag notwithstanding, I didn’t sleep all night.”

What follows are a few things that kept us up at night.

BEST DRESSED

A tie between two floors and four flues: The flooring in James Huniford’s atrium wore coyote fur and crocodile-printed recycled leather, while that in Eve Robinson’s elegant, if improbable, Modern Family room (improbable because it proposes a decorous night of Scrabble played by a family of four hopped up on marshmallows) wore silvery-gray pony skin, sliced up and stitched together.

As for the fireplaces, West Chin stuffed his outdoor hearth full of succulents; Ms. Robinson sheathed hers in polished stainless steel and filled it with silver blown-glass logs by the artist Suzan Etkin; Sara Story set out an armful of somber black “art” candles by Celine Cannon; and Mr. Levy covered his with faux brick laid in a herringbone pattern and a clear acrylic fire screen.

OVERDRESSED

The front hall, covered in a black floral sheer by Andrew Suvalsky that looked like the negligee of a Miami matron. “I just say, Go for it,” Mr. Suvalsky said. “As you can see, I’m equal opportunity about color.”

His walls were lacquered, variously, in black, gray, yellow and blue. There were hot-pink satin pillows on a red velvet sofa. He designed the turquoise-blue and white lacquer cabinets himself and collected a quartet of Adrien Broom photos (think Marilyn Minter by way of Gregory Crewdson) to mount above them. In one, a tiny toy cowboy marches into a model’s lipsticked mouth. “I don’t know what those people are doing, but I’d really like to,” Mr. Suvalsky said. “Is he going into her mouth, or pulling something out of it?”

UNDRESSED

On the night stand of the house’s only bedroom, in a framed print of her new ad for Scalamandré, Kathryn Ireland, the English-born Los Angeles designer and cast member of “Million Dollar Decorators” on Bravo, plays “La Grande Odalisque,” after the painting by Ingres, wearing only a swag of white sheeting and a pair of silk tassels.

DECOMPRESSED

Mariette Himes Gomez and Brooke Gomez, her daughter, presented a monochromatic English sitting room that manages to seat 14 (instead of a coffee table, there is a four-foot-square ottoman). “It’s become the ladies’ lounge,” they said.

Ms. Story decided that surrealism and the fractured planes of Cubism were the best expressions of a designer’s state of mind. On the walls of her sitting room, there was a trippy, black-and-white stylized bamboo wallpaper that was extrapolated, she said, from doodles she used to make in art school. Ms. Story also designed a pair of lavender sofas to look like the shifting planes of a Cubist painting. The bathroom, tiled entirely in black-and-white squares, was a homage both to Andrée Putman and to Ms. Story’s own anxieties, she said. She had filled the bathtub with crumpled paper scrawled with phrases like “Bamboo: Hate or Love?”

“It’s all my insecurities about my work,” Ms. Story said. “All the thoughts you have at 3 a.m. I just wanted to be real and genuine. To talk about design and not decoration, and how do you get there, and how do you know when it is enough?”

In every dream home, a heartache.

The Kips Bay Decorator Show House is open through June 4 at 161 East 64th Street, $35: (718) 893-8600, extension 245; kipsbay.org.